I would like to see the phone used either as a trackpad or as a notifications window in the dock. I use an application called GMote with my phone, and I can tell you that I quickly adjusted to navigating and controlling my PC's cursor from the phone screen one-handed. It would be quite easy to slide the phone into the dock like a cartridge and use it like a trackpad. In fact, I was a bit surprised the I first saw the Atrix attached to the backside of its laptop dock!
I think that with the laptop form factor and the cartridge-style phone loading capability, you have the opportunity to dedicate a significant portion of the housing to battery capacity, speakers, full-size HDMI, webcam...the list goes on and on... We could easily see a whole new set of apps written for the laptop environment too, lets see OpenOffice, Ardour, GIMP, Blender, Pidgin, Firefox, Thunderbird all compiled for RISC/ARM 2Ghz Quads and Tegra 4...
There is literally nothing stopping this from happening. Heck it could be done be your average basement Linux enthusiast with a liters of Mt Dew Code Red and an industrial sack of Cool Ranch Doritoes!